Are these files necessary?

I just found these files/folders in c:\Windows. They may have been around for awhile but I don't recall seeing them.

Numerous files like "KB885836.log"
Numerous folders like "$NtInstallKB890175$" containing files like "spuninst" and "agentdpv.dll"

Can some please tell me what these are and whether I can/should delete them or not?

Thanks!

Patches and service packs leave log files when they install themselves (windows update, etc).
I'd bet these are from that.

Use Start -> Programs -> System Tools -> Disk Cleanup
if you're worried about space. (assuming you have that: I do)

Oh, and it should go without saying that you don't delete files in the Windows, WindowsNT, System, System32, etc directories unless you're very familiar with fixing your computer.

Thanks very much Nikki!

Yeah if you look under add/remove programs you'll see down at the bottom of the list you can remove individual hotfixes that have been applied to your system, those files are so the fixes can be uninstalled. Though I still wouldn't recommend deleting them manually yourself. I think you might be able to get rid of them through disk clean up but maybe not.